Pneumatic tube apparatus and systems have long been known, and have been particularly adapted to drive-up banking. In such banking systems a number of exterior customer stations are located in a vehicle drive-through area. Each customer station has a terminal connected by a pneumatic tube or conduit to a teller terminal located at a remote point, such as a bank building. A carrier is pneumatically transported between teller and customer terminals through conduits to effect banking transactions. The carrier is typically drawn and/or pushed through the conduits by air pressure differentials across the carrier created in the conduit, the pressure differentials being typically supplied by a blower creating positive or negative air pressure within the conduit to effect carrier movement.
Many of the pneumatic carrier systems of this type provide for the horizontal delivery of the carrier, at least at the customer station. A sliding, axially traversed (i.e., horizontally moving), cover has been employed to open and close the terminal at the customer station to permit access thereto for insertion and removal of the carrier from the terminal. With the carrier in the terminal and the cover closed, the terminal is pressurized to effect movement of the carrier to another station.
Sliding covers of the foregoing type typically slide on tracks. Dust and debris falling on the tracks and sliding off the cover onto the tracks can build up on the track surface to the point where binding of the cover takes place. This has been recognized to be a problem particularly in customer terminals located in dusty areas, such as in the U.S. Southwest. The problem has been specifically noted with terminal covers having an outwardly extending flange located along the bottom of the cover which slides in a "C" or "U" shape track element. Binding of the cover by dust and the like building up in this type of relatively enclosed track can present an acute problem.